Database Reference
In-Depth Information
Chapter 10
Deciding Query Entailment in
Fuzzy OWL Lite Ontologies
Jingwei Cheng
Northeastern University, China
Z. M. Ma
Northeastern University, China
Li Yan
Northeastern University, China
ABSTRACT
Significant research efforts in the Semantic Web community are recently directed toward the representa-
tion and reasoning with fuzzy ontologies. Description logics (DLs) are the logical foundations of standard
Web ontology languages. Conjunctive queries are deemed as an expressive reasoning service for DLs.
This chapter focuses on fuzzy (threshold) conjunctive queries over knowledge bases encoding in fuzzy
DL
SHIF (
D
, the logic counterpart of fuzzy OWL Lite language. It shows decidability of fuzzy query
entailment in this setting by providing a corresponding tableau-based algorithm. The chapter shows
data complexity for answering fuzzy conjunctive queries in fuzzy
SHIF (
D
is in coNP, as long as only
simple roles occur in the query. Regarding combined complexity, this research proves a co3NExpTime
upper bound in the size of the knowledge base and the query.
INTRODUCTION
The Semantic Web is an extension of the current Web in which the Web information can be given well-
defined semantics, and thus enabling better cooperation between people and computers. In order to
represent and reason with structured knowledge in the Semantic Web, W3C has developed and recom-
mended the Web Ontology Language (OWL) (Bechhofer, Van Harmelen, Hendler, Horrocks, McGuin-
ness, Patel-Schneider, Stein, et al., 2004), which comprises three sublanguages of increasing expressive
power: OWL Lite, OWL DL and OWL Full. Description logics (DLs) (Baader, Calvanese, McGuinness,
